Symbol-display system

ABSTRACT

This invention discloses a symbol-display subscriber unit for use with a broadcast system, the broadcast system including a headend and a network operative to transmit a composite signal from the headend to a multiplicity of subscriber units, the composite sigincluding an encoded broadcast signal encoded in accordance with a plurality of control words (CWs) and a plurality of encryption control messages (ECMs), each of the plurality of ECMs being associated respectively with one of the plurality of CWs and including CW generating information, the multiplicity of subscriber units including at least one said symbol-display subscriber unit, said symbol-display subscriber unit including: a receiver receiving the composite signal from the network, security apparatus in operative engagement with the receiver, the security apparatus receiving each of the plurality of ECMs from the receiver and generating the associated CW from the CW generating information comprised within each said ECM. and a decoder for decoding the encoded broadcast signal for display on a display device, the decoder receiving the encoded broadcast signal from the receiver and receiving the CW from the security apparatus, wherein the security apparatus supplies symbol display information to the decoder, and the decoder provides a symbol to the display device for display thereon, the symbol being based, at least in part, on the symbol display information. A method for producing a symbol is also disclosed.

FIELD OF THE INVENTION

The present invention relates to apparatus and methods for displaying ormaking sensible a symbol or a mark, in particular in cases where thesymbol or mark is associated with an encoded message.

BACKGROUND OF THE INVENTION

Systems for displaying a symbol on a television display are well knownin the art.

U.S. Pat. No. 3,928,845 to Clark describes a character generator systemsuitable for use in a television broadcast controller.

U.S. Pat. No. 5,253,067 to Chaney et al describes a system to allow auser to select preprogrammed labels for widely used television networks.

Japanese published application 57-65974 describes a character multiplexbroadcast TV receiver having a memory for displaying a symbolic patternrepresenting a concealed display.

Systems for scrambling a television transmission are also well known inthe art. The terms “scramble” and “encode”, in their various grammaticalforms, are used interchangeably throughout the present specification andclaims to refer to any method suitable for scrambling or encoding atelevision transmission. The terms “descramble” and “decode”, in theirvarious grammatical forms, are similarly used interchangeably throughoutthe present specification and claims to refer to any method suitable forrendering a scrambled or encoded television transmission suitable forviewing. Many such methods are known in the art; examples of methods inwide use include “cut-and-rotate”, described, for example, in U.S. Pat.No. 4,070,693 to Shutterly, and DES encryption, as described below.

One system for scrambling a television data stream is described in U.S.Pat. Nos. 5,282,249 and 5,481,609, both to Cohen et al. Scrambledtelevision transmissions described in the Cohen et al. patents includeboth scrambled data representing television signals and coded controlmessages, also known in the art as ECMs. The ECMs of Cohen et al.include, in a coded form, data necessary for generating a control word(CW) which may be used to descramble the scrambled data representingtelevision signals.

Data necessary for generating a control word is known in the prior artto take many different forms and may include, in general, at least anyof the following: a control word; an encrypted control word which isintended to be decrypted before use, and a seed to a generating functionsuch as, for example, a one-way function which generates the controlword upon input of the seed. Throughout the present specification andclaims the terms “control word generating information” and “CWgenerating information” are used interchangeably to designate datanecessary for generating a control word in any appropriate form, asdescribed above.

While the two patents to Cohen et al. describe an analog system, thatis, a system in which analog television data streams are broadcast totelevision sets, it is appreciated that similar ECM methods may also beused for digital television data streams. Generally, the scramblingtechniques used for scrambling analog television signals such as, forexample, the well known “cut-and-rotate” technique, are chosen for theirapplicability to analog signals. In scrambling of digital televisionsignals other scrambling techniques, well-known in the art, are used,the techniques being more appropriate to digital signals such as, forexample, applying the well-known DES algorithm to the digital televisionsignals.

A typical prior art system for scrambling and descrambling a televisiontransmission is shown in FIG. 1. In the prior art system of FIG. 1, aremovable security element such as a smart card is used to derive a CWfrom CW generating information included in an ECM and to supply the CWto a decoder for use in descrambling a scrambled television signal.

Methods of transmitting a scrambled digital signal, including ECMs, arewell known. The prior art system of FIG. 1 may use a composite signal,that is, an analog or digital signal including more than one component,typically including both a scrambled television signal and ECMs. Priorart references which discuss examples of this type of signal include thefollowing: DVB ETR289, “Digital Video Broadcasting (DVB): Support foruse of scrambling and conditional access (CA) within digitalbroadcasting systems”; and DVB SIM061, “Technical specification ofDVB-Simulcrypt”, Apr. 1 1997.

Other documents relating to broadcasting of digital information includethe DVB Specification for Data Broadcasting, document SI-DAT 360 (TM1779), Feb. 12 1997; and ATSC Digital Television Standard, document A54,October 1995 and subsequent editions.

Other methods of transmitting a scrambled digital signal, particularlyuseful in a case where the signal includes sub-signals encoded accordingto various different methods, are described in “Common InterfaceSpecification for Conditional Access and other Digital VideoBroadcasting Decoder Applications”, DVB document A017, May 1996 andsubsequent editions; and in “Common Interface Specification forConditional Access and other Digital Video Broadcasting DecoderApplications”, CENELEC EN0221:1997.

The disclosures of all references mentioned above and throughout thepresent specification are hereby incorporated herein by reference.

SUMMARY OF THE INVENTION

The present invention seeks to provide an improved apparatus and methodsfor displaying or making sensible a symbol or a mark, in particular incases where the symbol or mark is associated with an encoded message. Ina preferred embodiment of the present invention, a symbol or mark isdisplayed on a display, particularly on a television display. It isappreciated that a mark, such as a trademark, may be sensible to a senseother than vision, and that the present invention is not limited in itsapplicability to visible marks.

The apparatus and method of the present invention are particularlyapplicable to encoded data systems, such as encoded data storage systemsand encoded data transmission systems. One particularly well-knownexample of such systems is encoded television systems. Throughout thepresent specification and claims, encoded television systems are oftendiscussed by way of example, without limiting the generality of thepresent invention. Other typical applications of the present inventioninclude, but are not limited to the following: other encoded broadcastsystems, such as encoded data broadcast systems; and non-broadcastsystems, such as systems for playing back a recording, particularlysystems for playing back an encoded recording.

In encoded television systems, it may be desirable to cause elements ofthe system which are responsible for decoding to display a symbol on atelevision display at a particular time. For example, it may bedesirable to display a symbol, such as a trademark, associated with avendor or with a product or service supplied by a vendor at the time ofa sale or offer for sale of a product or service. In the presentspecification and claims, the terms “symbol”, “mark”, and “trademark”are used interchangeably to refer to any sensible emblem, token, orsign, particularly of the kinds suitable for use as a trademark.

While the various embodiments of the present invention are generallydescribed below with reference to display of a symbol or mark, it isappreciated that the symbol or mark may be provided as an output and notdirectly displayed, and the symbol may or may not be further processed,including processing for display, after being produced by the presentinvention.

It may further be desirable to associate such a symbol with the decodingof encoded television signals in such a way that the decoding equipmentis required to supply the symbol for display in order to ensure properdecoding of the encoded signal.

There is thus provided in accordance with a preferred embodiment of thepresent invention a symbol-display subscriber unit for use with abroadcast system, the broadcast system including a headend and a networkoperative to transmit a composite signal from the headend to amultiplicity of subscriber units, the composite signal including anencoded broadcast signal encoded in accordance with a plurality ofcontrol words (CWs) and a plurality of encryption control messages(ECMs), each of the plurality of ECMs being associated respectively withone of the plurality of CWs and including CW generating information, themultiplicity of subscriber units including the at least onesymbol-display subscriber unit, the symbol-display subscriber unitincluding a receiver receiving the composite signal from the network,security apparatus in operative engagement with the receiver, thesecurity apparatus receiving each of the plurality of ECMs from thereceiver and generating the associated CW from the CW generatinginformation included within each the ECM, and a decoder for decoding theencoded broadcast signal for display on a display device, the decoderreceiving the encoded broadcast signal from the receiver and receivingthe CW from the security apparatus, wherein the security apparatussupplies symbol display information to the decoder, and the decoderprovides a symbol to the display device for display thereon, the symbolbeing based, at least in part, on the symbol display information.

There is also provided in accordance with another preferred embodimentof the present invention a broadcast system including a headend, anetwork operative to transmit signals from the headend to a multiplicityof subscriber units including at least one symbol-display subscriberunit, the symbol-display subscriber unit including a receiver receivingfrom the network a composite signal including an encoded broadcastsignal encoded in accordance with a plurality of control words (CWs),and a plurality of encryption control messages (ECMs), each of theplurality of ECMs being associated respectively with one of theplurality of CWs and including CW generating information for generatingthe associated CW, security apparatus in operative engagement with thereceiver, the security apparatus receiving each of the plurality of ECMsfrom the receiver and generating the associated CW from the CWgenerating information included within the ECM, and a decoder fordecoding the encoded signal for display on a display device, the decoderreceiving the encoded signal from the receiver and receiving the CW fromthe security apparatus, wherein the security apparatus supplies symboldisplay information to the decoder, and the decoder provides a symbol tothe display device for display thereon, the symbol being based, at leastin part, on the symbol display information.

Further in accordance with a preferred embodiment of the presentinvention the security apparatus includes removable security apparatusin removable operative engagement with the receiver.

Still further in accordance with a preferred embodiment of the presentinvention the removable security apparatus includes a smart card.

There is also provided in accordance with another preferred embodimentof the present invention security apparatus for use with asymbol-display subscriber unit of a broadcast system, the broadcastsystem including a headend and a network operative to transmit signalsfrom the headend to a multiplicity of subscriber units including atleast one the symbol-display subscriber unit, the symbol-displaysubscriber unit including a receiver receiving from the network acomposite signal including an encoded broadcast signal encoded inaccordance with a plurality of control words (CWs) and a plurality ofencryption control messages (ECMs), each of the plurality of ECMs beingassociated respectively with one of the plurality of CWs and includingCW generating information for generating the associated CWs, thesecurity apparatus being operatively engageable with the receiver andwith a decoder operative to decode encoded signals using at least one CWand to provide a symbol to a display device based on symbol displayinformation, the security apparatus including a CW generation unitreceiving each of the plurality of ECMs from the receiver and generatingthe associated CW from the CW generating information included within theECM, and a symbol display information unit for supplying the symboldisplay information to the decoder.

Further in accordance with a preferred embodiment of the presentinvention the security apparatus includes a symbol display informationstorage area for storing the symbol display information.

Still further in accordance with a preferred embodiment of the presentinvention at least one of the plurality of ECMs includes the symboldisplay information.

Additionally in accordance with a preferred embodiment of the presentinvention the CW includes the symbol display information.

Moreover in accordance with a preferred embodiment of the presentinvention the CW generating information includes a seed to a generatingfunction for generating a CW.

Further in accordance with a preferred embodiment of the presentinvention the symbol is based, at least in part, on symbol displayinformation included within at least two ECMs.

Still further in accordance with a preferred embodiment of the presentinvention the symbol display information includes a representation ofthe symbol.

Additionally in accordance with a preferred embodiment of the presentinvention the symbol display information includes generating informationfor generating the symbol.

Moreover in accordance with a preferred embodiment of the presentinvention at least one of the plurality of ECMs includes controlinformation for controlling display of the symbol.

Further in accordance with a preferred embodiment of the presentinvention the symbol display information includes symbol displayinstructions, and the decoder executes the symbol display instructions.

Still further in accordance with a preferred embodiment of the presentinvention the decoder is operative to decode the encoded broadcastsignal based, at least in part, on the symbol display information.

Additionally in accordance with a preferred embodiment of the presentinvention the symbol includes a trademark.

Moreover in accordance with a preferred embodiment of the presentinvention the broadcast system includes a television broadcast system,and the network includes a television network, and the encoded broadcastsignal includes an encoded television signal.

There is also provided in accordance with another preferred embodimentof the present invention encoded information including symbol displayinformation, wherein the symbol display information includes informationfor decoding the encoded information.

There is also provided in accordance with another preferred embodimentof the present invention a method for producing a symbol, the methodincluding decoding encoded information based, at least in part, onsymbol display information, and producing a symbol based, at least inpart, on the symbol display information.

Further in accordance with a preferred embodiment of the presentinvention the encoded information includes an encoded transmission.

Still further in accordance with a preferred embodiment of the presentinvention the method also includes displaying the symbol on a display.

Additionally in accordance with a preferred embodiment of the presentinvention the method includes presenting the symbol on a virtual realitydevice.

Moreover in accordance with a preferred embodiment of the presentinvention the method includes presenting the symbol in a manner which issensible to at least one human sense.

Further in accordance with a preferred embodiment of the presentinvention the method includes retrieving the symbol display informationfrom a symbol display information storage area.

Still further in accordance with a preferred embodiment of the presentinvention the method also includes receiving an encryption controlmessage (ECM) including the symbol display information.

There is also provided in accordance with another preferred embodimentof the present invention a method for decoding encoded information, themethod including receiving the encoded information, and decoding theencoded information based, at least in part, on symbol displayinformation.

Further in accordance with a preferred embodiment of the presentinvention the encoded information includes an encoded transmission.

Still further in accordance with a preferred embodiment of the presentinvention the encoded information includes the symbol displayinformation.

Additionally in accordance with a preferred embodiment of the presentinvention the method also includes receiving decoding information,wherein the decoding information includes the symbol displayinformation.

There is also provided in accordance with another preferred embodimentof the present invention a method for displaying a symbol on a displaywithin a television system, the method including transmitting an encodedtelevision signal, transmitting a plurality of encryption controlmessages (ECMs) each including CW generating information for computing acontrol word (CW) for decrypting the encoded television signal, at leastone of the plurality of ECMs also including symbol display information,computing the CW from the CW generating information, and sending the CWand the symbol display information to a decoder.

There is also provided in accordance with another preferred embodimentof the present invention a symbol-display decoding unit for use withencoded information, the encoded information including an encodedinformation signal encoded in accordance with plurality of control words(CWs) and a plurality of encryption control messages (ECMs), each of theplurality of ECMs being associated respectively with one of theplurality of CWs and including CW generating information, thesymbol-display decoding unit including receiving apparatus for receivingthe encoded information, security apparatus in operative engagement withthe receiving apparatus, the security apparatus receiving each of theplurality of ECMs from the receiving apparatus and generating theassociated CW from the CW generating information included within eachECM, and a decoder for decoding the encoded information signal, thedecoder receiving the encoded information signal from the receiver andreceiving the CW from the security apparatus, wherein the securityapparatus supplies symbol display information to the decoder, and thedecoder provides a symbol in a format suitable for further processing,the symbol being based, at least in part, on the symbol displayinformation.

Further in accordance with a preferred embodiment of the presentinvention the symbol-display decoding unit also includes data playbackapparatus for supplying the encoded information to the receivingapparatus.

Still further in accordance with a preferred embodiment of the presentinvention the symbol-display decoding unit also includes virtual realityapparatus for receiving the symbol from the decoder and for providing avirtual reality display of the symbol.

Additionally in accordance with a preferred embodiment of the presentinvention the security apparatus is adapted to receive at least oneconditional access (CA) module, the at least one CA module beingoperative to receive each of the plurality of ECMs from the securityapparatus, generate the associated CW from the CW generating informationincluded within each the ECM, and supply the symbol display informationto the security apparatus.

Moreover in accordance with a preferred embodiment of the presentinvention the at least one CA module includes a plurality of CA modules.

Further in accordance with a preferred embodiment of the presentinvention only one of the plurality of CA modules provides the symboldisplay information for each of the plurality of ECMs.

Still farther in accordance with a preferred embodiment of the presentinvention more than one of the plurality of CA modules provides thesymbol display information for at least one of the plurality of ECMs.

There is also provided in accordance with another preferred embodimentof the present invention a symbol-display decoding method for use withencoded information, the encoded information including an encodedinformation signal encoded in accordance with plurality of control words(CWs) and a plurality of encryption control messages (ECMs), each of theplurality of ECMs being associated respectively with one of theplurality of CWs and including CW generating information, the methodincluding receiving the encoded information, receiving each of theplurality of ECMs and generating the associated CW from the CWgenerating information included within each ECM, and decoding theencoded information signal, the decoding step including receiving theencoded information signal from the receiver, and receiving the CW fromthe security apparatus, and supplying symbol display information forproviding a symbol in a format suitable for further processing, thesymbol being based, at least in part, on the symbol display information.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully fromthe following detailed description, taken in conjunction with thedrawings in which:

FIG. 1 is a simplified partly pictorial, partly block diagramillustration of a prior art encoded television system;

FIG. 2A is a simplified partly pictorial, partly block diagramillustration of a symbol display encoded television system constructedand operative in accordance with a preferred embodiment of the presentinvention;

FIG. 2B is a simplified partly pictorial, partly block diagramillustration of a symbol display encoded television system constructedand operative in accordance with an alternative preferred embodiment ofthe present invention;

FIG. 3A is a simplified block diagram illustration of a preferredembodiment of the smart card of FIG. 2A;

FIG. 3B is a simplified block diagram illustration of a preferredembodiment of the smart card of FIG. 2B;

FIG. 4 is a simplified flowchart illustration of a preferred method ofoperation of the systems of FIGS. 2A and 2B;

FIG. 5 is a simplified partly pictorial, partly block diagramillustration of a symbol display encoded information system constructedand operative in accordance with an alternative preferred embodiment ofthe present invention;

FIG. 6 is a simplified partly pictorial, partly block diagramillustration of a symbol display encoded virtual reality systemconstructed and operative in accordance with another alternativepreferred embodiment of the present invention;

FIG. 7 is a simplified partly pictorial, partly block diagramillustration of a symbol display encoded playback system constructed andoperative in accordance with still another preferred embodiment of thepresent invention; and

FIG. 8 is a simplified partly pictorial, partly block diagramillustration of a symbol display encoded television system constructedand operative in accordance with yet another preferred embodiment of thepresent invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Reference is now made to FIG. 2A which is a simplified partly pictorial,partly block diagram illustration of a symbol display encoded televisionsystem constructed and operative in accordance with a preferredembodiment of the present invention. As explained above, it isunderstood that the present invention is not limited to a televisionsystem, but may be applicable to any broadcast system including a databroadcast system, or a data playback or retrieval system of any kind. Itis also appreciated that the present invention may be used in a contextin which data is displayed on a display or otherwise rendered availablefor access by a user such as, for example, by printing, by presentationwith a virtual reality device, by any other kind of sensory inputdevice, by storage on any appropriate storage medium for later access,etc. The specific example of a television system is used to simplify thedescription of the present invention, and is not intended to limit thegenerality of the foregoing.

The system of FIG. 2A preferably comprises a headend 100, which may besimilar to conventional headend systems which are well known in the art.The system of FIG. 2A also typically comprises a broadcast medium suchas a satellite 105. It is appreciated that any appropriate broadcastmedium, such as, for example, cable or terrestrial broadcast media,including digital or analog broadcast media, may be used instead of thesatellite 105.

The headend 100 typically broadcasts a composite signal 110 via thebroadcast medium such as the satellite 105, the composite signal 110typically comprising at least a scrambled television signal andassociated ECMs, as described below. As described below in more detailwith reference to FIG. 5, it is appreciated that the scrambled signaland the associated ECMs may be provided separately rather than ascomponents of a composite signal.

The system of FIG. 2A also preferably comprises a subscriber unit 115.Typically, a multiplicity of subscriber units 115 is provided, only onesubscriber unit 115 being shown in FIG. 2A in order to simplify thedescription of the present invention. It is appreciated that, inpractice, up to a large number of subscriber units, such as millions ofsubscriber units, may be used.

The subscriber unit 115 typically comprises an IRD (integrated receiverdecoder) 120 which may be similar to IRD units which are well known inthe art, except as described below. The IRD 120 typically receives thecomposite signal 110 via an antenna 123 and associated cabling, or byany other appropriate means.

The IRD 120 typically comprises a receiver 125 and a decoder 130, eachof which may be implemented in software and hardware by conventionalmeans. The receiver 125 is operatively associated with the decoder 130,typically being operative to tune the received composite signal 110, toseparate components of the composite signal 110, and to send a scrambledtelevision signal comprised in the composite signal 110 to the decoder130.

The subscriber unit 115 also typically comprises a removable securityelement such as a smart card 135. The smart card 135 may be generallysimilar to removable security elements well-known in the art, such as inthe prior art system of FIG. 1, except as described below. Typicalfunctions performed by a prior art smart card are described in U.S. Pat.Nos. 5,282,249 and 5,481,609, both to Cohen et al., referred to above.

The receiver 125 is also typically operative to send ECMs comprised inthe received composite signal 110 to the smart card 135. The smart card135 typically receives the ECMs from the receiver 125 and suppliesinformation, as described below, to the decoder 130.

While a removable security element such as the smart card 135 istypically used and is generally described throughout the presentspecification and claims, it is appreciated that a non-removablesecurity element, such as a security element comprised within the IRD120, may also be used. In such a case, the non-removable securityelement would preferably function similarly to a removable securityelement, except for being non-removable.

The subscriber unit 115 also typically comprises a display 140,operatively attached to the decoder 130 and receiving suitable displaysignals therefrom. The display 140 may be any suitable display, such asa conventional television apparatus. It is appreciated that the display140 and the display signals sent by the decoder 130 are chosen so as tobe compatible, typically in conformance to a standard, as is well knownin the art.

The operation of the apparatus of FIG. 2A is now briefly described. Thereceiver 125 separates the incoming composite signal 110 into aplurality of components, typically comprising at least a scrambledtelevision signal and a plurality of ECMs, one ECM 145 being shown inFIG. 2A. As described above, it is conventional in scrambled televisionsystems for a plurality of ECMs to each comprise CW generatinginformation for generating a CW. The smart card 135 is typicallyoperative to generate the CW from the CW generating information 150 andsupply the CW to the decoder 130 for decoding a segment of the scrambledtelevision signal which is associated with and may be descramble usingthe CW. Typically, the CW changes frequently such as, for example, everyfew seconds, and thus a new segment of scrambled television signal,which may be descramble with a new CW, is broadcast every few secondsalong with an associated ECM as previously described.

In the embodiment of FIG. 2A the ECM 145 preferably also comprisessymbol display information 155 for generating a symbol 160 for displayon the display 140. It is appreciated that the symbol 160 may take anyappropriate form, including, for example: one or more characters; apicture; an animated picture; an icon; a trademark; or any combinationof the above.

It is also appreciated that the symbol display information 155 may takeany appropriate form including, for example: a bitmap of the symbol 160;a compressed bitmap of the symbol 160; generating information that maybe used by the decoder 130 to generate the symbol 160; one or moreprogrammed instructions that may be used by the decoder 130 to generatethe symbol 160; an address of the symbol 160 within a memory (not shown)of the decoder 130; an indication for choosing a symbol from a pluralityof symbols associated with the decoder 130 and typically stored therein;a character-based representation of the symbol 160, such as, forexample, an ASCII representation; a font-based representation of thesymbol 160, such as, for example, an indication as to which character orcharacters in a font may be used to generate the symbol 160; ananimation-based representation of the symbol 160; a description of thesymbol 160 in a graphic description language; any other appropriaterepresentation of the symbol 160; an indication to utilize a specificcomponent of the composite signal 100 for producing the symbol 160; anyother appropriate means; or any appropriate combination of the above.

It is also appreciated that, although the symbol display information 155is shown as separate from the CW generating information 150, the symboldisplay information 155 may alternatively be comprised in the CWgenerating information 150. In such a case, a portion of the CWgenerating information 150 typically serves not only as CW generatinginformation but also as the symbol display information 155. Whichportion of the CW generating information 150 serves as the symboldisplay information 155 may be predetermined, may be determinedaccording to information comprised within the ECM 145, or may bedetermined by other suitable means.

It is further appreciated that the amount of symbol display information155 necessary to generate the symbol 160 may be greater than a maximumamount of information that can be accommodated within one ECM 145,particularly in a typical case where the ECM 145 has a fixed size andother information, such as the CW generating information 150, is alsocomprised within the ECM 145. In such a case, it is appreciated that thesymbol generating information 155 from a plurality of ECMs 145 may becombined together, either within the smart card 135 or, typically,within the decoder 130, in order to form the full symbol generatinginformation necessary to generate the symbol 160. It is appreciated thatmany methods of sending a message in segments and assembling thesegments together into the full message are well known in the art, andthat any appropriate such method may be used to combine symbol displayinformation 155 from a plurality of ECMs 145.

It is also appreciated that the symbol display information 155, oranother portion of the ECM 145, may include control informationcontrolling the display of the symbol 160 on the display 140. Suchcontrol information may include, for example, one or more of thefollowing: an instruction to begin displaying the symbol 160; aninstruction to cease displaying the symbol 160; an instruction to placethe symbol 160 at a particular location on the display 140; aninstruction to animate the symbol 160; an instruction to cease animatingthe symbol 160; or any other appropriate control instruction. Typically,the decoder 130 is operative to act on the control information when thecontrol information is received by the decoder 130.

It may be desirable to verify that the symbol display informationprovided by the smart card 135 is identical to the symbol displayinformation 155 that was contained in the ECM 145, or to symbol displayinformation known to the headend 100 but not transmitted. In such acase, the decoder 130 may perform any appropriate operation using the CWand the symbol display information provided by the smart card 135 inorder to produce a final version of the CW for use in decoding thescrambled television transmission, the scrambled television signalhaving been scrambled for decoding with the final version of the CW. Byway of example only and without limiting the generality of theforegoing, the decoder 130 may concatenate the CW and the symbol displayinformation in order to produce a final version of the CW. It isappreciated that other appropriate operations may be used to produce thefinal version of the CW.

It is appreciated that performing an operation combining the CW and thesymbol display information, as described above, ensures that the smartcard 135 provides the correct symbol display information; otherwise, thescrambled television signal will not be correctly descramble because thefinal version of the CW will be incorrect. It is also appreciated that,in a case where the symbol 160 comprises a trademark, it may bepreferable to ensure that the trademark symbol is correctly supplied bythe smart card 135, and in such a case verification of the symboldisplay information provided by the smart card 135 is preferred.

Reference is now made to FIG. 2B, which is a simplified partlypictorial, partly block diagram illustration of a symbol display encodedtelevision system constructed and operative in accordance with analternative preferred embodiment of the present invention. The system ofFIG. 2B is similar to the system of FIG. 2A, except as described below.

The system of FIG. 2B comprises an ECM 165, which in turn comprises theCW generating information 150. The ECM 165 need not comprise the symboldisplay information 155 which is comprised in the ECM 145 of FIG. 2A.The system of FIG. 2B also comprises a smart card 170, which may besimilar in structure and function to the smart card 135 of FIG. 2A,except that the smart card 170 of FIG. 2B comprises symbol displayinformation 173, which may be similar to the symbol display information155 of FIG. 2A but which is typically stored within the smart card 170in any appropriate manner, as is well-known in the art for storing datawithin a smart card.

The operation of the system of FIG. 2B is similar to the operation ofthe system of FIG. 2A, except that the symbol display information 155 isstored in the smart card 170 and is typically provided to the decoder130 for display based on control information, as described above withreference to FIG. 2A.

Reference is now made to FIG. 3A, which is a simplified block diagramillustration of a preferred embodiment of the smart card 135 of FIG. 2A.The smart card 135 typically comprises a CW generation unit 175 and asymbol display information unit 180, each of which is typicallyimplemented in software and hardware, as is well-known in the art. TheCW generation unit 175 is preferably operative, as described above withreference to FIG. 2A, to produce a CW from received CW generatinginformation comprised in an ECM. The symbol display information unit 175is typically operative, as described above with reference to FIG. 2A, toproduce symbol display information from symbol display informationcomprised in the ECM.

Typically, the CW generation unit 175 may receive the entire ECM andforward the symbol display information to the symbol display informationunit 180, particularly in a case where the symbol display information iscomprised in the ECM. Alternatively, both the CW generation unit 175 andthe symbol display information unit 180 may receive the entire ECM andeach preferably operates only on a relevant portion of the ECM. Furtheralternatively, a combination of both methods may be used. Still furtheralternatively, the CW generation unit 175 and the symbol displayinformation unit 180 may be combined in a single unit.

Reference is now made to FIG. 3B, which is a simplified block diagramillustration of a preferred embodiment of the smart card 170 of FIG. 2B.The structure and operation of the smart card 170 is similar to that ofthe smart card 135 of FIG. 3A, except that, in place of the symboldisplay information unit 180 of FIG. 3A the smart card 170 comprises asymbol display information storage unit 185. The symbol displayinformation storage unit 185 typically comprises a suitable memorydevice, such as a ROM or an EE-PROM as are well known in the art. Thesymbol display information storage unit 185 is typically operative tostore symbol display information and to supply the symbol displayinformation on command, typically on command received from the CWgeneration unit 175 or otherwise.

The information stored in the symbol display storage information unit185 may be stored at the time of manufacture of the smart card 170; maybe written into the symbol display storage information unit 185 at thetime of personalization of the smart card 170 for a particular customer;may be broadcast over the air to the smart card 170; may be chained fromdata comprised in a previously-used smart card, as is well known in theart in a case where smart cards are periodically changed; may be storedin the IRD 120 or in a removable conditional access module (not shown inFIG. 3B) or may be provided for storage by any other appropriate method.

Reference is now made to FIG. 4, which is a simplified flowchartillustration of a preferred method of operation of the systems of FIGS.2A and 2B. The method of FIG. 4 preferably comprises the followingsteps:

Security apparatus, typically comprising removable security apparatussuch as a smart card, supplies display information to a decoder, such asa decoder in a scrambled television system (step 190). Preferably, thedecoder uses the display information, typically as part of a process fordetermining a control word used to decode scrambled transmissions (step195).

Optionally, the decoder demands display information again from theremovable security apparatus; typically the information is demanded uponreceipt of a broadcast command, periodically, or randomly (step 200). Ina case where the display information is intended to display a trademarkat the time that goods and/or services are sold or offered for sale,including step 200 in the method of FIG. 4 is preferred.

Preferably, as part of step 200, the decoder may compare the displayinformation received in step 200 with the display information suppliedby the removable security apparatus in step 190, and may refuse tocontinue to operate if the display information received in step 200 doesnot match the display information received in step 190. In this way,since the display information supplied in step 190 is essential indetermining a control word in step 195, the decoder may ensure that thedisplay information provided for display in step 200 matches specific,predetermined display information used in step 195.

The decoder supplies a symbol, based on the display information, to adisplay; the symbol is typically provided periodically and/or uponreceipt of a broadcast command (step 205).

Reference is now made to FIG. 5, which is a simplified partly pictorial,partly block diagram illustration of a symbol display encodedinformation system constructed and operative in accordance with analternative preferred embodiment of the present invention. The apparatusof FIG. 5 comprises a decoding and symbol generation unit (DSGU) 210.

The DSGU 210 preferably comprises a decoder 215, which may be similar instructure and function to the decoder 130 of FIGS. 2A and 2B, describedabove. The DSGU 210 also preferably comprises security apparatus 220,which may be similar in structure and function to the smart card 135 ofFIG. 2A or, alternatively, to the smart card 170 of FIG. 2B. As in otherembodiments of the present invention, it is appreciated that thesecurity apparatus 220 may comprise any appropriate security apparatus,removable or non-removable.

The operation of the apparatus of FIG. 5 is now briefly described. Thedecoder 215 typically receives a scrambled information signal from asource external to the DSGU 210. The scrambled information signal may ormay not be a television signal and may be broadcast or may be suppliedby other suitable means well known in the art, including via anysuitable network or via a wired connection.

The security apparatus 220 typically receives an ECM, which may besimilar to the ECM 145 of FIG. 2A or to the ECM 165 of FIG. 2B. The ECMmay be broadcast or may be supplied by other suitable means well-knownin the art. The ECM may originate from the same source as the scrambledinformation, or may originate from another source.

The security apparatus 220 is typically operative to produce a CW andsymbol display information and to provide the CW and the symbol displayinformation to the decoder 215. The CW and the symbol displayinformation may be as described above with reference to FIGS. 2A and 2Band may be produced in a manner similar to that described above withreference to FIGS. 2A and/or 2B.

The decoder 215 is preferable operative to process the scrambledinformation and the CW and the symbol display information in a mannersimilar to that described above with reference to the decoder 130 ofFIGS. 2A and 2B and to output unscrambled information and a symbol.

More generally, it is appreciated that a wide variety of methods may beused to associate symbol display information with scrambled information.For example and without limiting the generality of the foregoing, thescrambled information may be scrambled in the sense that it is deliveredin a format not generally known, and the scrambled information includestherein symbol display information which is also used to convert theformat of the scrambled information to a generally accepted format forfurther processing or display.

Reference is now made to FIG. 6, which is a simplified partly pictorial,partly block diagram illustration of a symbol display encoded virtualreality system constructed and operative in accordance with anotheralternative preferred embodiment of the present invention. The system ofFIG. 6 is similar to the systems of FIGS. 2A and 2B, except that ascrambled virtual reality signal is supplied and descramble, thedescramble virtual reality signal and symbol display information beingthen supplied to virtual reality apparatus 230, which may comprise anyappropriate virtual reality apparatus well-known in the art. The symbol160 is seen as incorporated into a virtual reality scene 240.

It is appreciated that, in a more general sense, a signal may be madesensible to any of the senses, such as the sense of smell, with a symbolthen comprising a particular smell, for example, so that the presentinvention is not limited to particular implementations of virtualreality.

Reference is now made to FIG. 7, which is a simplified partly pictorial,partly block diagram illustration of a symbol display encoded playbacksystem constructed and operative in accordance with still anotherpreferred embodiment of the present invention. The system of FIG. 7 issimilar to the systems of FIGS. 2A and 2B except that the broadcastsource, the headend 100 of FIG. 2A, is replaced with a playback device250, which may be any suitable playback device such as, for example, adigital video disk (DVD playback device).

It is appreciated that the principles and apparatus described above withreference to FIGS. 2A and 2B are also applicable to the systems of FIGS.6 and 7. It is further appreciated that the various output devices shownin FIGS. 2A, 2B, 6, and 7 are shown by way of example only, and anyother output device such as, for example, a suitable recording device,may also be used.

Reference is now made to FIG. 8, which is a simplified partly pictorial,partly block diagram illustration of a symbol display encoded televisionsystem constructed and operative in accordance with yet anotherpreferred embodiment of the present invention. The embodiment of FIG. 8is suitable to a common interface system.

In a common interface system, as is well-known in the art, a pluralityof encoded inputs from different providers are typically combinedtogether into a composite signal, each encoded input typically requiringa method different from the other coded inputs for producing a CW froman ECM. In prior art common interface systems, as described, for examplein “Common Interface Specification for Conditional Access and otherDigital Video Broadcasting Decoder Applications”, referred to above, theproblem of applying the correct method to each ECM is solved byproviding one or more removable CA modules which are typically connectedto an IRD in a chained manner, with a first CA module being connected tothe IRD and subsequent CA modules being connected to the previous CAmodule. Each CA module is then operative to translate the appropriateECMs belonging to a corresponding coded input.

It is appreciated that the description of the CA modules as being“chained”, and the depiction thereof in FIG. 8, are meant to describethe logical data flow between CA modules and that various methods ofphysical connection, including methods described in “Common InterfaceSpecification for Conditional Access and other Digital VideoBroadcasting Decoder Applications”, referred to above, may be used. Thecurrent description is not meant to be limited to any particular methodof physical connection.

The apparatus of FIG. 8 comprises an IRD 260, which in turn comprises areceiver 125 and a decoder 130 which may be similar to those of FIG. 2A.The IRD 260 is adapted to receive a first CA module 265 which may besimilar to common interface CA modules known in the art. The first CAmodule 265 is typically in removable operative attachment with a firstsmart card 270, which may be similar to the smart card 150 of FIG. 2Aand which similarly comprises symbol display information 155.

A second CA module 275 and second smart card 280, similar in structureand function to the first CA module 265 and the first smart card 270 arealso shown in FIG. 8, it being understood that, alternatively, eitherone CA module or a plurality of CA modules may be provided.

The operation of the system of FIG. 8 may be similar to the operation ofthe systems of FIGS. 2A and 2B, with the one of the CA modules 265 or275, and associated smart card 270 or 280, which produces the CW alsoproducing the symbol display information. It is appreciated thatalternative modes of operation may also be possible, with more than oneCA module producing symbol display information, including more than oneCA module producing symbol display information for one ECM, or with oneCA module producing the CW and another producing the symbol displayinformation.

It is appreciated that various features of the invention which are, forclarity, described in the contexts of separate embodiments may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention which are, for brevity, described in thecontext of a single embodiment may also be provided separately or in anysuitable subcombination.

It will be appreciated by persons skilled in the art that the presentinvention is not limited by what has been particularly shown anddescribed hereinabove. Rather the scope of the invention is defined onlyby the claims which follow:

What is claimed is:
 1. A symbol-display subscriber unit for use with abroadcast system, the broadcast system comprising a headend and anetwork operative to transmit a composite signal from the headend to amultiplicity of subscriber units, the composite signal comprising anencoded broadcast signal encoded in accordance with a plurality ofcontrol words (CWs) and a plurality of encryption control messages(ECMs), each of the plurality of ECMs being associated respectively withone of the plurality of CWs and comprising CW generating information,the multiplicity of subscriber units comprising at least one saidsymbol-display subscriber unit, said symbol-display subscriber unitcomprising: a receiver receiving the composite signal from the network;security apparatus in operative engagement with the receiver, thesecurity apparatus receiving each of the plurality of ECMs from thereceiver and generating the associated CW from the CW generatinginformation comprised within each said ECM; and a decoder for decodingthe encoded broadcast signal for display on a display device, thedecoder receiving the encoded broadcast signal from the receiver andreceiving the CW from the security apparatus, wherein the securityapparatus supplies symbol display information to the decoder, and thedecoder provides a symbol to the display device for display thereon, thesymbol being based, at least in part, on the symbol display information.2. A broadcast system comprising: a headend, a network operative totransmit signals from the headend to a multiplicity of subscriber unitscomprising at least one symbol-display subscriber unit, saidsymbol-display subscriber unit comprising: a receiver receiving from thenetwork a composite signal comprising: an encoded broadcast signalencoded in accordance with plurality of control words (CWs); and aplurality of encryption control messages (ECMs), each of the pluralityof ECMs being associated respectively with one of the plurality of CWsand comprising CW generating information for generating the associatedCW; security apparatus in operative engagement with the receiver, thesecurity apparatus receiving each of the plurality of ECMs from thereceiver and generating the associated CW from the CW generatinginformation comprised within said ECM; and a decoder for decoding theencoded signal for display on a display device, the decoder receivingthe encoded signal from the receiver and receiving the CW from thesecurity apparatus, wherein the security apparatus supplies symboldisplay information to the decoder, and the decoder provides a symbol tothe display device for display thereon, the symbol being based, at leastin part, on the symbol display information.
 3. Apparatus according toeither claim 1 or claim 2 and wherein the security apparatus comprisesremovable security apparatus in removable operative engagement with thereceiver.
 4. Apparatus according to claim 3 and wherein the removablesecurity apparatus comprises a smart card.
 5. Security apparatus for usewith a symbol-display subscriber unit of a broadcast system, thebroadcast system comprising a headend and a network operative totransmit signals from the headend to a multiplicity of subscriber unitscomprising at least one said symbol-display subscriber unit, saidsymbol-display subscriber unit comprising a receiver receiving from thenetwork a composite signal comprising an encoded broadcast signalencoded in accordance with a plurality of control words (CWs) and aplurality of encryption control messages (ECMs), each of the pluralityof ECMs being associated respectively with one of the plurality of CWsand comprising CW generating information for generating the associatedCWs, the security apparatus being operatively engageable with thereceiver and with a decoder operative to decode encoded signals using atleast one CW and to provide a symbol to a display device based on symboldisplay information, the security apparatus comprising: a CW generationunit receiving each of the plurality of ECMs from the receiver andgenerating the associated CW from the CW generating informationcomprised within said ECM; and a symbol display information unit forsupplying the symbol display information to the decoder.
 6. Apparatusaccording to any of the above claims and wherein said security apparatuscomprises a symbol display information storage area for storing saidsymbol display information.
 7. Apparatus according to any of the aboveclaims and wherein at least one of the plurality of ECMs comprises saidsymbol display information.
 8. Apparatus according to any of thepreceding claims and wherein said CW comprises said symbol displayinformation.
 9. Apparatus according to any of the preceding claims andwherein said CW generating information comprises a seed to a generatingfunction for generating a CW.
 10. Apparatus according to any of thepreceding claims and wherein said symbol is based, at least in part, onsymbol display information comprised within at least two ECMs. 11.Apparatus according to any of the preceding claims and wherein saidsymbol display information comprises a representation of said symbol.12. Apparatus according to any of the preceding claims and wherein saidsymbol display information comprises generating information forgenerating said symbol.
 13. Apparatus according to any of the precedingclaims and wherein at least one of said plurality of ECMs comprisescontrol information for controlling display of said symbol. 14.Apparatus according to any of the preceding claims and wherein saidsymbol display information comprises symbol display instructions, andsaid decoder executes the symbol display instructions.
 15. Apparatusaccording to any of the preceding claims and wherein said decoder isoperative to decode the encoded broadcast signal based, at least inpart, on the symbol display information.
 16. Apparatus according to anyof the preceding claims and wherein the symbol comprises a trademark.17. Apparatus according to any of the preceding claims and wherein thebroadcast system comprises a television broadcast system, and thenetwork comprises a television network, and the encoded broadcast signalcomprises an encoded television signal.
 18. Encoded informationcomprising symbol display information, wherein the symbol displayinformation includes information for decoding the encoded information.19. A method for producing a symbol, the method comprising: decodingencoded information based, at least in part, on symbol displayinformation; and producing a symbol based, at least in part, on thesymbol display information.
 20. A method according to claim 19 andwherein the encoded information comprises an encoded transmission.
 21. Amethod according to either claim 19 or claim 20 also comprising:displaying the symbol on a display.
 22. A method according to eitherclaim 19 or claim 20 and also comprising: presenting the symbol on avirtual reality device.
 23. A method according to either claim 19 orclaim 20 and also comprising: presenting the symbol in a manner which issensible to at least one human sense.
 24. A method according to any ofclaims 19-23 and also comprising: retrieving the symbol displayinformation from a symbol display information storage area.
 25. A methodaccording to any of claims 19-24 and also comprising: receiving anencryption control message (ECM) comprising the symbol displayinformation.
 26. A method for decoding encoded information, the methodcomprising: receiving the encoded information; and decoding the encodedinformation based, at least in part, on symbol display information. 27.A method according to claim 26 and wherein the encoded informationcomprises an encoded transmission.
 28. A method according to eitherclaim 26 or claim 27 and wherein the encoded information comprises thesymbol display information.
 29. A method according to any of claims26-28 and also comprising: receiving decoding information, wherein thedecoding information comprises the symbol display information.
 30. Amethod for displaying a symbol on a display within a television system,the method comprising: transmitting an encoded television signal;transmitting a plurality of encryption control messages (ECMs) eachcomprising CW generating information for computing a control word (CW)for decrypting said encoded television signal, at least one of saidplurality of ECMs also comprising symbol display information; computingsaid CW from said CW generating information; and sending said CW andsaid symbol display information to a decoder.
 31. A symbol-displaydecoding unit for use with encoded information, the encoded informationcomprising an encoded information signal encoded in accordance with aplurality of control words (CWs) and a plurality of encryption controlmessages (ECMs), each of the plurality of ECMs being associatedrespectively with one of the plurality of CWs and comprising CWgenerating information, said symbol-display decoding unit comprising:receiving apparatus for receiving the encoded information; securityapparatus in operative engagement with the receiving apparatus, thesecurity apparatus receiving each of the plurality of ECMs from thereceiving apparatus and generating the associated CW from the CWgenerating information comprised within each said ECM, and a decoder fordecoding the encoded information signal, the decoder receiving theencoded information signal from the receiver and receiving the CW fromthe security apparatus, wherein the security apparatus supplies symboldisplay information to the decoder, and the decoder provides a symbol ina format suitable for further processing, the symbol being based, atleast in part, on the symbol display information.
 32. Apparatusaccording to claim 31 and also comprising: data playback apparatus forsupplying the encoded information to the receiving apparatus. 33.Apparatus according to either claim 31 or claim 32 and also comprising:virtual reality apparatus for receiving the symbol from the decoder andfor providing a virtual reality display of the symbol.
 34. Apparatusaccording to any of claims 31-33 and wherein the security apparatus isadapted to receive at least one conditional access (CA) module, the atleast one CA module being operative to: receive each of the plurality ofECMs from the security apparatus; generate the associated CW from the CWgenerating information comprised within each said ECM; and supply thesymbol display information to the security apparatus.
 35. Apparatusaccording to claim 34 and wherein the at least one CA module comprises aplurality of CA modules.
 36. Apparatus according to claim 35 and whereinonly one of the plurality of CA modules provides the symbol displayinformation for each of the plurality of ECMs.
 37. Apparatus accordingto claim 35 and wherein more than one of the plurality of CA modulesprovides the symbol display information for at least one of theplurality of ECMs.
 38. A symbol-display decoding method for use withencoded information, the encoded information comprising an encodedinformation signal encoded in accordance with plurality of control words(CWs) and a plurality of encryption control messages (ECMs), each of theplurality of ECMs being associated respectively with one of theplurality of CWs and comprising CW generating information, said methodcomprising: receiving the encoded information; receiving each of theplurality of ECMs and generating the associated CW from the CWgenerating information comprised within each said ECM; and decoding theencoded information signal, the decoding step comprising: receiving theencoded information signal from the receiver; and receiving the CW fromthe security apparatus; and supplying symbol display information forproviding a symbol in a format suitable for further processing, thesymbol being based, at least in part, on the symbol display information.